Ditto, fatter tires, lower pressure. Until we're holding 25-30 mph average over distance, the aero penalty isn't enough to offset the advantages.
I switched from 700x23 to 700x25 on one bike and from 700x20 to 700x23 on another. I usually run the 700x25 tires at 90 psi rear, 70 front, and could go lower. Much more comfortable -- I don't feel beaten up after miles and hours on chipseal -- and no slower. But my average speed over distances of 20-50 miles is only 16 mph, so the main aero factor is my own body, position and clothing, not the bike or tire size.
If my bikes could handle it I'd run 700x28 tires, but there's only enough clearance for 700x25 unless I modify the brake bridge and calipers.
If money is no object there are tires made especially for racing on cobbles and similarly rough terrain. Especially if we're willing to switch to tubulars. Those tires cost around $75 or more each.
And double wrap bar tape. Yeah, it's a little heavier and thicker so it's less aero. Won't make any difference for most of us mere mortals. On my Trek 5900 carbon bike I use generic black foam tape, over-wrapped with Arundel Synth Gecko. Much more comfortable. And I'm about to try 700x25, if the new tires I ordered will fit.
Some folks use bar tape or other thin padding on pedals to reduce vibration on the feet. I haven't tried that yet, but might give it a try on my old Look pedals if it doesn't interfere with clipping in securely.
Good insoles also help. Profoot Miracle insoles cost less than $10 and are the best I've found. Very thin and lightweight but effective in reducing hotspots on metatarsals.